Semaglutide vs Tirzepatide
Category
Metabolic & GLP-1
Metabolic & GLP-1
Class
GLP-1 receptor agonist (synthetic peptide analog)
Dual GIP/GLP-1 receptor agonist (synthetic peptide)
Regulatory status
FDA-approved (Ozempic, Rybelsus for type 2 diabetes; Wegovy for weight management)
FDA-approved (Mounjaro for type 2 diabetes; Zepbound for weight management)
Mechanism
Semaglutide is a long-acting analog of glucagon-like peptide-1 (GLP-1), an incretin hormone the gut releases after eating. It activates the GLP-1 receptor on multiple tissues.
Tirzepatide is a single peptide that activates both the GIP and GLP-1 receptors, two incretin pathways involved in glucose control and appetite.
Evidence summary
Semaglutide has a strong human evidence base. Large randomized trials (the SUSTAIN, PIONEER, and STEP programs) showed substantial reductions in HbA1c and body weight, and a cardiovascular outcomes trial showed reduced major cardiovascular events in people with type 2 diabetes. It is one of the most studied metabolic peptides.
Tirzepatide has strong human evidence from the SURPASS (diabetes) and SURMOUNT (obesity) trial programs, which showed large reductions in HbA1c and body weight, in several comparisons exceeding those seen with single GLP-1 agonists. It is a well-studied, approved medicine.
Reported safety
Common side effects are gastrointestinal (nausea, vomiting, diarrhea, constipation), usually strongest when starting or increasing the dose. It carries a boxed warning about thyroid C-cell tumors based on rodent data, and should be used only under medical supervision.
The most common side effects are gastrointestinal (nausea, diarrhea, vomiting, constipation), typically dose-related. Like other incretin drugs it carries a boxed warning about thyroid C-cell tumors based on rodent data and requires medical supervision.